There is nothing wrong with the friction sway control that you have.
Many millions of miles have been traveled using them. They are the original and in some ways the best ever made....BUT,,, over 25" or 5000# requires TWO of them.
I do not think that is the root of the problem though, as sway controls should be thought of as insurance, for less than ideal situations. Gusty winds, passing semis etc. Not as a band aid to cover the real problem.
You likely have two real problems. Too little tounge weight, made worse by a loose steering box.
Fix those two, and the sway will go away to the point where you may be tempted to forgo the second sway control.....Don't. You really do need it with that size TT.